code: def test_remove_features_subsets(logs, base_extractor, metric_name):
      next_subsets = remove_features_subsets(
          logs, base_extractor, metric_name, num_removed_by_step=1
      )
      assert sorted(next_subsets) == [("first",), ("second",)]
  
file_path: fklearn/tests/tuning/test_samplers.py
imports: import pandas
  import pytest
  from tests import LOGS, PARALLEL_LOGS
  from toolz.curried import first
  from fklearn.metrics.pd_extractors import evaluator_extractor
  from fklearn.training.classification import logistic_classification_learner
  from fklearn.tuning.samplers import remove_by_feature_importance, remove_by_feature_shuffling, remove_features_subsets
  from fklearn.validation.evaluators import roc_auc_evaluator
label_desc: Use image node_id 10 for calling a global function with example usage: test_remove_features_subsets(logs, base_extractor, metric_name) without return types